1. Field of the Invention
The present invention relates to hearing aids and to methods of operating hearing aids. The invention, more particularly relates to logging in a hearing aid of data pertaining to the acoustical environment.
2. Prior Art
A publication Cummings, K. L., & Hecox, K. E. (1987). “Ambulatory testing of digital hearing aid algorithms”, RESNA '87 proceedings of the 10th Annual Conference on Rehabilitation Technology Jun. 19-23, 1987 San Jose Calif., 389-400, suggests a portable unit for serving as a prototype hearing aid for testing signal processing algorithms. For providing an acoustic description of the listening environment, maximal and minimal sound pressure levels are recorded each of a number of sampling epochs, the minimal value assumed to represent the background noise level and the maximal value assumed to represent the speech level. The data may be represented in histogram form. The processor reads switch toggling. The unit is designed to permit retrospectively correlating the statistics of the patient's decisions and the environmental acoustics.
A publication “Description of MemoryMate/HA fitting. Data logging.” 13th Danavox Symposium October 1988, 392-393, explains a hearing aid with multiple program memories and with data logging for keeping track of how many times the wearer has selected a specific memory and the total time each memory has been used.
EP-B-335542 describes an auditory prosthesis having data logging capabilities. The memory may permit recording of environmentally selected events, such as selection of settings, parameters, or algorithms, where such selection is based on an automatic computation in response to the current sound environment of the wearer. In a preferred embodiment, the method of determining the values for each of the data logs entails counting time in large segments, of the order of two minutes (128 seconds). Duration of use of each setting is then stored in units of two minutes. In a modified embodiment, the datalogging may be implemented in a remote control unit. The hearing aid has an interface permitting sending datalogging information to a programmer.
EP-A-1367857 shows logging or recording input signal data of a hearing prosthesis in combination with values of algorithm parameters of a digital signal processing algorithm executed in the prosthesis. The input signal data may comprise the digital input signal itself or the digital input signal may be recorded in a data-reduced form. The input signal data may comprise spectral features and temporal features of the digital input signal. The input signal data may comprise statistical measures, such as long-term average spectra, peak and minimum spectra, average or peak instantaneous input sound pressure levels, amplitude distributions statistics etc., of the digital input signal. Input signal data may be intermediately recorded in a volatile storage device, e.g. a data RAM. The intermediate data may subsequently be stored in the persistent data space at a substantially more infrequent rate. In event-driven data logging, the input signal data and the values of the hearing prosthesis variable may be recorded before and after a relevant trigger-event. A flexible histogram module can map various types of numerical data to a histogram and store a set of histogram data.
U.S. Pat. No. 6,862,359 suggests obtaining real life sound recordings by passing a signal through an input signal path of a target hearing prosthesis.
WO-A-01/54456 suggests collecting statistical data characterising physical or psychological properties of environments in which use of a hearing aid is desired. Data to collect could include levels and spectral distributions of sound across time. The hearing aid may act as a data collector.
US-A-20040190739 relates to a method for recording information in a hearing device or in a recording unit. Acoustic signals may be recorded by the microphone. Statistical data, as e.g. the amplitude percentile, or general spatial or spectral level distribution, acoustic characteristics over an adjustable time interval, sound type distribution, and sound type adjustment distribution, may be stored. The user or the fitter can trigger logging manually.
EP-B-0732036 explains a processing circuit for a hearing aid, which circuit contains a control circuit for continuous determination of a percentile value of the input signal from a continuous analysis and evaluation of the frequency or amplitude distribution of the input signal.
Logging in a hearing aid of data about the acoustical environment is subject to severe constraints pertaining to size, memory capacity, processor capacity and power consumption.
Logging of data about the acoustical environment in a dedicated device, separate from the hearing aid, may easy the constraints but only comes against the penalty of not getting the true acoustic environment at the level of the hearing aid microphone, therefore being of less value with a view to providing data for permitting optimising the hearing aid settings.
The logging data will normally be available to a fitter who will transfer the logging data from the hearing aid during a fitting session. Normally, the fitter must initially program the hearing aid according to general fitting rules. The user will then start using the hearing aid, and he or she will in most cases later revert for a follow-up session, where he or she can discuss the initial experience and any desires for fine-tuning. The fitter can then advise and adjust as appropriate. A logging of data about the intrinsic behaviour of the hearing aid and about the acoustic environment would be a major advantage for understanding and investigating options for improving the programming, as well as for tracking any malfunctions in the hearing aid.
There is an interest for collecting a lot of data in order that the user can aggregate sufficient data for an early follow-up visit to the fitter, if necessary. This requires a high sampling rate in the logging. On the other hand, there is a desire for providing also long-time logging, e.g. logging for the entire service life of the hearing aid, a desire that is not compatible with a high sampling rate in the logging.
Thus, there is a need for improved hearing aids as well as improved techniques for logging of data pertaining to the acoustic environment.